Lubricant-coolant

ABSTRACT

WATER SOLUBLE POLYACRYLAMIDE POLYMERS NEUTRALIZED WITH AN ETHYLENE-MALEIC ANHYDRIDE COPOLYMER HAVE BEEN FOUND EXTREMELY EFFECTIVE AS A COMBINED LUBRICANT-COOLANT WHEN USED IN AQUEOUS SOLUTIONS IN METAL WORKING OPERATIONS.

United States Patent 3,563,895 LUBRICANT-COOLANT Vladimir Janatka, Woodbury, and Eugene P. Kirwan,

Wolcott, Conn., assignors to Valgene Industrial Research Corporation, Wolcott, Conn., a corporation of Connecticut N0 Drawing. Filed Oct. 25, 1968, Ser. No. 770,862

Int. Cl. Cm 1/28 US. Cl. 252--34.7 6 Claims ABSTRACT OF THE DISCLOSURE Water soluble polyacrylamide polymers neutralized with an ethylene-maleic anhydride copolymer have been found extremely effective as a combined lubricant-coolant when used in aqueous solutions inmetal working operations.

This invention relates to a novel composition useful as a lubricant-coolant in metal working operations. More particularly, the invention relates to a water soluble high molecular weight polymer based on acrylamide which is eminently suited for limited reduction of friction and for increased cooling effect in operations where a metal is subjected to physical deformation.

Many problems arise in operations involving metalworking machines, such as rolls, which are extremely complex and not fully explainable. For example, excessive lubricity will cause the working rolls to slip on the surface of the rolled material, and insufficient lubricity will cause spalling between the rolls and the rolled metal. In addition, there is the problem of surface finish, and it is not fully understood why a particular lubricating oil will produce better surface on rolled strip material than another oil.

Similar conditions are encountered in metal forming and cutting operations. In cutting operations, the cutting tool should be lubricated sufficiently to minimize friction but not excessively so as to hinder a positive bite of the tool into the metal being cut. In all of these operations, the lubricant must also serve as an efficient coolant.

The object of this invention, accordingly, is not to produce a super lubricant above which would diminish as much as possible the friction between two surfaces subjected to moving contact. It is an object of this invention to produce a fluid whose lubricity could be varied so as to adjust it to a level which would ideally suit the condition of various metal Working operations While at the same time acting as a coolant.

Materials presently used are oil and soap emulsions. These compositions have met these complex problems with only limited success. Even should the lubrication conditions be satisfied with this type of oil base lubricant, sec ondary problems are encountered such as staining of the product, excessive foaming of the emulsion, stability and bacterial deterioration.

In accordance with the present invention, a highly successful lubricant-coolant has been developed which is based on a solution of an acrylamide polymer in water. While polyacrylamides have been used to a limited degree as an additive in very small quantity to oil and soap compositions, its use has not solved the many problems alluded to above. As an additive to an oil-based lubricant, the viscosity of the base compound has been increased with ice consequent improvement of the hydrodynamic film between the moving metal parts. In contrast, it is here proposed to use an acrylamide derived polymer not as an additive but as the main component of the lubricant and in the absence of an oil. In essence, it has been found that by varying the concentration of the acrylamide polymer, it is possible to achieve exactly the optimum degree of lubricity and viscoelasticity of the lubricating fluid in order to overcome the various problems heretofore encountered. Generally, a viscosity of higher than 100 SSU at F is preferred.

Among the polymers found suitable in this invention, a preferred embodiment is a commercially available product sold by Dow Chemical Company under the designation Separan AP 30, believed to have the formula by the addition of ethylene maleic anhydride having the structure ong- -om- -on -on 0:. i=0] 6H 6H where n is an integer such that the molecular weight is 10,000 to 50,000.

In operation, best results were obtained when the solution was at a pH of 7 to 7.5. The resulting solution is a combination of an acrylic polymer and an acid form of an ethylene copolymer. In order to impart rust inhibition and detergency to the solution, other ingredients may be added. The purpose of these additives is to impart anticorrosion properties, defoaming properties and to form an oxidation preventive coating upon the metal surfaces so as to prolong the shelf life of the metal product. Additives having these properties which have been employed with success include, but are not limited to, zinc diamyldithiocarbamate, zinc dialkyl-phosphorodithiotate and various types of acrylic polymers.

A preferred composition of this invention is prepared by first making a basic solution consisting of approximately 3% of the polymerand 97% of water. This solution is then neutralized by the addition of an ethylene maleic anhydride copolymer of the type previously described. The needed detergency and rust preventive qualities are supplied by the selection of the proper additives as already mentioned.

Generally, the formulations found suitable may be compounded as follows:

Polymer-3% Ethylene-maleic anhydride copolymer (quantity for desired pH) Methacrylate polymer-1 to 3% Zinc dialkyl-phosphorodithiotatel to 5% Water-remainder of composition The rust inhibitor and the detergent additives may vary in composition and percentage. The initial or stock solution is then further dissolved in water depending upon the particular metal-working operation involved so as to obtain the optimum degree of lubricity required. Accordingly, in the final lubricant composition, the polymer may comprise from about 0.15% to 3.0% by weight of the over-all composition.

Successful metal working processes of many types have been carried out with the present composition. The following table is exemplary of these operations and of the concentrations of polymer employed when the concentrated composition described in the preceding paragraph is diluted in water in the following concentrations:

It will be obvious to those skilled in the art, that the components of the present compositions are variable with respect to intended use and range of viscosity required for such use.

We claim:

1. A lubricant-coolant composition for working metal surfaces comprising an aqueous solution which contains viscosity increasing amounts of a water soluble polyacrylamide polymer having the formula where n is an integer such that the molecular weight is at least 2,000,000 which polymer has been partly neutralized with an ethylene-maleic anhydride copolymer having the formula CH2CHzCH-CH a.) $20] (I)H (|)H u wherein n is an integer such that the molecular weight is 10,000 to 50,000, said solution having a pH of 7 to 7.5 and a viscosity above 100 SSU at 70 F.

2. The composition of claim 1 having in addition a small quantity of a methacrylate polymer.

3. The composition of claim 1 in which the polyacrylamide polymer comprises from about 0.15 to 3.0% by weight of the composition.

4. The composition of claim 2 in which the methacrylate polymer comprises from about 1.0 to 3.0% by weight of the composition.

5. The composition of claim 1 containing small quantities of a detergent, a rust inhibitor and an anti-foaming agent.

6. The composition of claim 5 containing from about 1.0 to 3.0% of a methacrylate polymer by weight of the composition.

References Cited UNITED STATES PATENTS 3,336,225 8/1967 Sayad et a1. 25234.7 3,402,137 9/1968 Fischer et al 26089.7X 3,418,157 12/1968 Katzer 25249.3 3,475,515 10/1969 Blatz et a1 26029.6HX

DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner US. Cl. X.R. 

